Methods and apparatus for fusionless treatment of spinal deformities

ABSTRACT

The treatment and correction of spinal deformities, such as scoliosis, is accomplished without the need for fusion of the intervertebral disc space. A surgical technique is provided in which opening and closing osteotomies are created in the affected vertebrae. Correction devices are provided which hold the osteotomies in either their closed or open orientations. The correction devices include bone-piercing anchors, some in the form of staples, holding the vertebral body on opposite sides of the body to retain the osteotomies in their desired orientation. In the opening osteotomies, the correction devices include a wedge member that is disposed within the opened wedge osteotomy and in contact with the vertebral body. The correction devices also include connection members which can be used to engage the devices to an elongated member spanning the spine, such as a spinal rod or a metal or non-metal cable or tether. Once bone union has occurred in the instrumented vertebrae, the spinal rod or cable or tether can be disconnected from the correction devices and removed from the patient. In another aspect of the invention, curvature deformities in two planes can be corrected using the same techniques and devices.

[0001] This patent application is a continuation-in-part of applicationSer. No. 08/892,604, filed Jul. 14, 1997.

BACKGROUND OF THE INVENTION

[0002] The present invention concerns instrumentation and techniques forthe treatment of spinal deformities. In particular, the inventivemethods and devices accomplish this treatment without the need forfusion of the spine.

[0003] Surgical intervention for the treatment of injuries to, anddeformities of the spine is approaching its first century. Nevertheless,the field of spinal surgery was not significantly advanced until thedevelopment of the hook and rod system by Dr. Harrington in the early1950's. Dr. Harrington developed this system in Houston when he begancare of children with progressive neuromuscular scoliosis secondary topolio. Until that time, the progressive scoliosis had been treated withexternal casts, which themselves yielded unacceptably high complicationrates. After a decade of development, the hook and rod system evolvedinto the form that is known today as the Harrington Instrumentation.

[0004] The original primary indication for use of HarringtonInstrumentation was in the treatment of scoliosis. Scoliosis is adeformity of the spine in the coronal plane, in the form of an abnormalcurvature. While a normal spine presents essentially a straight line inthe coronal plane, a scoliotic spine can present various lateralcurvatures in the coronal plane. The types of scoliotic deformitiesinclude thoracic, thoracolumbar, lumbar or can constitute a double curvein both the thoracic and lumbar regions.

[0005] Early techniques for correction of scoliosis utilized ahalo-traction device. In this technique, a halo is fixed to the skulland a vertical force is applied to the spine through the skull. In ahalo-femoral traction approach, the patient is supine and tractionforces are applied through a halo and a femoral pin. In a halo-gravitytraction procedure, the patient sits in a wheelchair and a suspendedweight applies a vertical force through the halo. In halo-pelvictraction, a pelvic ring is affixed to the patient and a series ofthreaded rods connect the cranial halo to the pelvic ring to apply anadjustable force separating the two rings. In procedures using the halo,the patient is either immobile or severely restricted in mobility.

[0006] To avoid the need for halos, various rod-based systems have beendeveloped. Of course, the original rod system for correction ofscoliosis is the Harrington System which utilized threaded and notchedrods. In particular, a typical Harrington System utilizes a notcheddistraction rod and at least one threaded compression rod, with thedistraction and compression rods being applied to the concave and convexportions of the curvature, respectively. In some procedures, a singledistraction rod spans across several thoracic and lumbar vertebrae. Thethreaded compression rods are then used to stabilize the rod fixation.In other approaches, the compression rod spans across the convex portionof the curve, such as between T₆ and L₂. In a Harrington procedure, ahook placed at the notched end of the distraction rod can beprogressively advanced toward the cranial end of the rod toprogressively correct the spinal deformation. At the same time, hooksengaged to the threaded compression rods can be drawn together on theconvex side of the curvature to assist in the correction and tostabilize the instrumented spine.

[0007] In an additional step of the Harrington procedure, once the spinehas been substantially corrected, transverse stabilization can be addedbetween the two rods extending on opposite sides of the spine.Importantly, for long term stability, bone graft is placed along theinstrumented vertebral levels to achieve fusion along that portion ofthe spine.

[0008] One drawback commonly associated with the Harrington System isthat the rods are completely straight. As a result, patients in which aHarrington System has been used to correct a scoliosis condition havebeen left with the so-called flat-back syndrome. Specifically, incorrecting the lateral curvature of the spine, the normal sagittal planecurvature is eliminated by the presence of a completely straight rod. Insome cases, it has been found that the patient is better off retainingthe scoliotic curvature than enduring the complications associated withflat-back syndrome. Another drawback is the requirement of bracing andcasting.

[0009] To address these problems, subsequent rod-based systems haverelied upon pre-bent spinal rods and multiple fixation sites.Specifically, the rods are bent to the normal thoracic kyphosis andlumbar lordosis in the sagittal plane. One such system is the Luquesegmental spinal instrumentation. In the early 1980's, Dr. Luquepioneered a technique for segmental correction of abnormal spinalcurvatures in which wires were used to affix vertebral levels to apre-bent rod. These sublaminar wires are used to help draw the vertebraetoward the rod and ultimately to hold the vertebrae in position. In oneapproach using Luque instrumentation, a unit rod is provided whichutilizes a single rod anchored at its ends to the ilium and bent at itscranial end so that two halves of the rod are oriented on opposite sidesof the spinal column. The unit rod can then be used as a lever tostraighten the spine, after which Luque sublaminar wires are used to fixthe vertebrae to the unit rod.

[0010] As with the Harrington System, the final step of the LuqueInstrumentation is frequently fusion of the instrumented spinalsegments. There have been suggestions for instrumentation without fusionto correct scoliosis in younger patients, this technique was believed topermit further spinal growth. However, the results of thisinstrumentation without fusion were not very promising and led tocertain complications, including loss of correction, reduced spinalgrowth and an unacceptable rate of instrumentation failure.

[0011] In yet another rod-based instrumentation system pioneered by Dr.Cotrel in France, a pre-curved rod is engaged to the vertebrae at theconcave side of the abnormal curvature. The rod is then rolled about itsaxis to derotate the scoliotic curvature and at the same time providethe instrumented segments with the normal sagittal plane curvature. Forinstance, in the correction of thoracic lordoscoliosis, rolling of apre-curved rod not only derotates the curvature in the coronal plane, italso transforms that scoliotic curvature into a physiological thoracickyphosis. The rod is held to the vertebrae by a series of hooks, whichare ultimately fixed to the rod once the derotation process is complete.To ensure a stable correction, an additional rod is added on theopposite side of the spinous process from the first rod. Members fortransversely connecting the two rods create a rigid scaffold areattached. Again, in this procedure, bone chips are placed along theinstrumented vertebrae to achieve fusion at the instrumentation site.

[0012] Other rod-based systems have been developed over the last severalyears that accomplish similar correction of spinal deformities, such asscoliosis. For example, the TSRH® Universal Spine System of DanekMedical, Inc. and the ISOLA® Spine System of AcroMed Corp. can beinstrumented to the spine to correct various types of spinaldeformities. In all of these rod-based Systems, the spinal rods arepermanently fixed to the patient's spine. Of course, once fusion of allthe instrumented levels has occurred, the original instrumentation islargely superfluous.

[0013] Other techniques that have been developed for correction ofspinal deformities are performed anteriorly from the convex side of theabnormal curvature. In this technique, the intervertebral discs areremoved and an osteotomy spreader is used to separate the adjacentvertebrae, thereby realigning the vertebral bodies in the coronal plane.A rod is attached to the spine via screws to maintain the correction.Fusion material, such as bone chips, are inserted into the widenedintervertebral disc spaces to ultimately achieve fusion at thosevertebral levels. Immobilization using an external cast or brace can beutilized while fusion is occurring.

[0014] A related technique involves Dwyer instrumentation that utilizesa flexible cable. In this technique, the cable is connected to theaffected vertebrae on the convex side of the curvature. The cable isthen shortened, thereby applying compression to the convex side of thecurvature. Once the curvature has been corrected using the Dwyer cable,ancillary instrumentation, such as a Harrington rod, can be added forfixing and stabilizing the spine. In the Dwyer instrumentation, Dwyerclamps are pressed into the vertebral bodies to provide a seat for theinsertion of Dwyer screws. The Dwyer screws define a channel throughwhich the Dwyer cable can pass to perform the compression and ultimatelythe derotation of the abnormal curvature.

[0015] A similar approach is taken using Zielke instrumentation, exceptthat the Dwyer cable is replaced by a pre-bent threaded rod. Applicationof the compressive forces to reduce the convex side of the curvatureoccurs by threaded nuts along the rod to translate the bone screwsengaged to the vertebrae. Failed fusion because of residual deformitycan be corrected by using posterior osteotomies which are closed andanterior wedges which are usually open. Following mobilization of thespinal segments by the osteotomies, then the spinal deformity can becorrected with instrumentation and then re-fused to maintain thecorrection.

[0016] While many techniques and instrumentation have been developed forthe correction of spinal deformities, none of which we were aware priorto our invention, had been devised that could achieve the necessarycorrection without fusion of the instrumented vertebral levels.Moreover, some of the techniques resulted in an undesirable flat-backsyndrome in which the normal sagittal plane curvature is eliminated. Inaddition, the prior systems greatly restrict the patient's normalmobility, and some restrict the growth of the spine. In the latterinstance, some of the spinal instrumentation is not acceptable for usein younger patients.

[0017] A need exists for a technique and system to correct spinaldeformities without the necessity of fusing the corrected vertebralsegments. A need also exists for a system and technique that canaccomplish this correction with minimal long-term invasion of thepatient.

SUMMARY OF THE INVENTION

[0018] In order to address these unmet needs, a method andinstrumentation are provided for correction of spinal deformitieswithout the need for fusion of the corrected segments. In one aspect ofthe invention, a surgical technique is provided in which osteotomies areclosed on the convex side of the curvature deformity and opened on theconcave side of the curvature. Mechanical wedges are engaged within theopen wedge osteotomies on the concavity of the curvature. The vertebralbodies will heal and form a unified body at the location of the closedosteotomies. In this manner, the normal coronal plane position of thespine is restored by elimination of the curvature deformity.

[0019] In a further aspect of the technique, the orientation of theopening or closing wedge osteotomies can be predetermined to achieve anormal curvature in the sagittal plane and normal spinal orientation inthe coronal plane. For example, the addition of mechanical wedges intoopening wedge osteotomies in the lumbar spine can be used to eliminatean abnormal lateral curvature while restoring the normal lordoticcurvature of the lumbar vertebrae.

[0020] In a further aspect of the technique, connection elements orfasteners are engaged to each of the vertebrae in which an osteotomy hasbeen performed. The connection element can then be engaged to anelongated member, such as a spinal rod, that has been pre-bent to theadjusted spinal curvature. The longitudinal member stabilizes the spineas the closing osteotomies heal and the mechanical wedges becomeintegrated into the vertebrae having the opening wedge osteotomies. Inthis manner, the intervertebral discs are maintained intact. Moreover,and perhaps most significantly, none of the vertebral levels are fusedtogether. Once the vertebral bodies have completely healed, thelongitudinal member can be removed. With this feature of the inventivetechnique, the normal mobility of the patient's spine is restored sincethe intervertebral discs are not fused.

[0021] In another aspect of the invention, instrumentation is providedthat can be used to perform the inventive technique. In one feature ofthe invention, the instrumentation includes a correction device thatincludes upper and lower anchors configured to penetrate a singlevertebral body at substantially opposite sides of the body. In threeillustrated embodiments of the instrumentation, the anchors are in theform of staples. In other illustrated embodiments, the anchors are insomewhat the form of a half staple or an adz. In all illustratedembodiments, a connection element is provided that extends between theupper and lower anchors and through the vertebral body. In oneimplementation, the connection element includes a threaded shank thatengages a mating threaded boss on the lower anchor. In anotherimplementation, the connection element has a threaded shank which isfixed to the lower anchor, and a head portion of the instrumentation isthreaded onto the shank. In both implementations, the connection elementcan be used to provide a compressive force between the upper and loweranchors, thereby retaining their position and engagement with thevertebral body.

[0022] In the various implementations, the connection element includes ahead portion adjacent the upper anchor. The head portion can beconfigured for connection to an elongated member used to stabilize thespine. In one embodiment, the head of the connection element isconfigured to engage an elongated spine rod. In another, it isconfigured for a spinal tethering function.

[0023] In accordance with a further feature of the invention, two typesof correction devices can be provided. One correction device is utilizedto close the closing wedge osteotomy in a vertebral body. In thiscorrection device, the connection element is used to engage an upper andlower anchor to the vertebral body. In the second correction device, amechanical wedge is attached to the lower anchor. The second correctiondevice is thus used in maintaining the opened wedge osteotomies on theconcavity of the curvature to be corrected. The mechanical wedge memberis situated within the open space created by the opening wedgeosteotomy. The anchors, stabilize the opening wedge osteotomy in aclosing direction around the mechanical wedge as the vertebral bodyheals. In some mild cases, adequate correction may be achieved withoutintervertebral rods, plates, cabling or tethering, and a furtherembodiment of the invention for such cases, is disclosed.

[0024] In accordance with the present invention, a method is providedfor correcting spinal deformities without the need ion fusion of thespine. A further object of the invention is accomplished by thetechnique and instrumentation that allows a stabilizing elongated memberto be used only temporarily. This aspect provides the benefit that theelongated member, such as the spinal rod, can be removed once theinstrumented vertebrae have healed, thereby restoring the normalmobility to the patient's spine.

[0025] Another object of the present invention is achieved by aspects ofthe technique and instrumentation that allows for adjustment of thespinal curvature in both the sagittal and the coronal planes. Stillother objects and certain benefits of the invention will be discernedfrom the following written description of the invention together withthe accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a side perspective view of a correction device used inconnection with the inventive method for treatment of spinaldeformities.

[0027]FIG. 2 is a side perspective view of a second type of correctiondevice used in this inventive technique, in which the correction deviceincludes a mechanical wedge member for placement within an opening wedgeosteotomy.

[0028]FIG. 3 is a top perspective view of a component of the correctiondevice shown in FIG. 2, particularly showing the mechanical wedgemember.

[0029]FIG. 4 is a top elevational view of the component shown in FIG. 3.

[0030]FIG. 5 is an end elevational view of the component shown in FIG.3.

[0031]FIG. 6 is a side elevational view of the component shown in FIG.3.

[0032]FIG. 7A is a view of the anterior aspect of a portion of thelumbar spine showing a correction device as depicted in FIG. 2 engagedwithin a vertebra.

[0033]FIG. 7B is a view in the coronal plane of the instrumentedvertebra in FIG. 7A with the correction device shown in cross-section.

[0034]FIG. 8 is a view from the anterior aspect of the spine of avertebral level with a correction device as depicted in FIG. 1 engagedwithin the vertebral body.

[0035]FIG. 9 is a side elevational view of an alternative embodiment ofa connection element for use with the correction devices shown in FIGS.1 and 2.

[0036]FIG. 10 is a top elevational view of the connection element shownin FIG. 9.

[0037]FIG. 11 is a schematic representation of a deformed spine anddepicting the locations of opening and closing wedge osteotomies.

[0038]FIG. 12 is a view of the spine shown in FIG. 11 with theosteotomies opened and closed in accordance with the inventivetechnique.

[0039]FIG. 13 is a view of the corrected spine shown in FIG. 12 with theinventive instrumentation engaged to the instrumented vertebral levels.

[0040]FIG. 14A is a view of a vertebra in the coronal plane showing anaxis for performing an osteotomy in conjunction with a method of thepresent invention.

[0041]FIG. 14B is an anterior to posterior view of the vertebra in FIG.14A in which the osteotomy site is shown in cross-hatch.

[0042]FIG. 14C is a lateral view of the vertebra in FIG. 14A in whichthe osteotomy site is shown in cross-hatch.

[0043]FIG. 15 is a perspective view of a correction device according tothe present invention and with further improvements.

[0044]FIG. 16 is a top plan view of a spinal rod receiving head of thecorrection device of FIG. 15.

[0045]FIG. 17 is an elevational view of the correction device of FIG.15.

[0046]FIG. 18 is a partial sectional view of the device taken at line18-18 in FIG. 17 and viewed in the direction of the arrows.

[0047]FIG. 19A is a view of the anterior aspect of a portion of thelumbar spine showing two of the correction devices of FIG. 15 engaged inadjacent vertebral bodies with a spinal rod fastened to them and shownfragmentarily.

[0048]FIG. 19B is a view of the correction device of FIG. 15 installedas in FIG. 19A and viewed in the coronal plane.

[0049]FIG. 20 is an elevational view of another embodiment of thecorrection device.

[0050]FIG. 21 is a section through the device of the FIG. 20 embodimenttaken at line 21-21 in FIG. 16 and viewed in the direction of thearrows.

[0051]FIG. 22 is a perspective view of the outer or top bone anchoringdevice of the FIG. 20 embodiment.

[0052]FIG. 23 is an elevational view thereof

[0053]FIG. 24 is a perspective view of the bottom or inner end boneanchoring device according to the FIG. 20 embodiment.

[0054]FIG. 25 is a plan view of the device of FIG. 24.

[0055]FIG. 26 is a view similar to FIGS. 7A and 19A but illustratingapplication of the embodiment of FIG. 20.

[0056]FIG. 27 is an elevational view of another embodiment of thecorrection device.

[0057]FIG. 28 is another elevational view of the device of FIG. 27rotated on its axis 90°.

[0058]FIG. 29 is a section therethrough taken at line 29-29 in FIG. 8and viewed in the direction of the arrows.

[0059]FIG. 30 is a elevational view of still a further embodiment of theinvention useful in a tethering application.

[0060]FIG. 31 is an elevational view thereof with the device turned 90°on its axis.

[0061]FIG. 32 is a section therethrough taken at line 32-32 in FIG. 31and viewed in the direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] For the purpose of promoting an understanding of the principlesof the invention, reference will now be made to preferred embodimentsthereof and specific language will be used to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the invention, and such further applications of theprinciples of the invention as described therein being contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

[0063] The present invention concerns apparatus and methods for use inthe correction of spinal deformities without the need for fusion ofadjacent vertebrae. In general terms, the inventive technique involvescreating opening and closing osteotomies in the affected vertebrae.Wedges of material are either removed or added to each vertebra asneeded to bring the vertebra into a normal spinal alignment. In anotheraspect of the technique, the opening/closing osteotomies are oriented inthe vertebral body so as to effect curvature corrections in both thesagittal and the coronal planes.

[0064] The inventive surgical techniques can be accomplished by novelcorrection devices for a closing osteotomy. One such correction devicecan include upper and lower staples that are engaged on essentiallyopposite sides of the vertebral body. A connection member spans betweenthe upper and lower staples to apply a slight compressive force to holdthe staples in position. The connection member itself can threadedlyengage the lower staple and can include an enlarged head to provide areaction surface as the threaded shank of the connection member passesthrough an opening in the upper staple.

[0065] The opening osteotomy can be retained by a connection device thatincludes similar upper and lower staples. In one modification, theopening osteotomy correction device includes a mechanical wedge memberattached to the lower staple. The wedge member fits within the osteotomysite to hold the osteotomy open and engage the vertebral body. A similarconnection member is provided that can be threaded into the wedge memberand that exerts a compressive force at an opening in the upper staple.

[0066] In both correction devices, the connection member can include ahead portion that is adapted to engage an elongated member spanning theaffected vertebrae. In one aspect of the invention, once the opening andclosing osteotomies have been perfected by way of the correctiondevices, the connection members can be engaged to the elongated member,such as a spinal rod, to stabilize the construct. Once bone union isachieved at the osteotomy sites, the spinal rod can be removed torestore the normal motion of the vertebral segments.

[0067] With this general description in mind, specific details of thecorrection devices can be seen with reference to FIGS. 1-10. Lookingfirst at FIG. 1, a correction device 10 is depicted that is used for theclosing osteotomy discussed above. The correction device 10 includes alower bone-piercing anchor 11, an upper bone-piercing anchor 12 and aconnection member 13. The lower anchor, in the form of a staple 11includes a pair of prongs 15 connected to and separated by a base plate16. The prongs 15 are configured to be pressed into the hard corticalbone of the vertebral body. Such prongs typically include a taperedcross-section to facilitate their insertion and can be of aconfiguration shown in U.S. Pat. No. 5,395,372, owned by the assignee ofthe present invention. The lower staple 11 also includes a threaded boss17 projecting from the base plate 16 in the same direction of the prongs15. The boss 17 is preferably cylindrical and includes an internallythreaded bore.

[0068] The upper anchor 12 of the correction device 10 is similarlyformed like a staple by upper prongs 20 attached to an upper plate 21.In accordance with the preferred embodiment, the upper staple 12 has agreater width between its prongs 20 than the lower staple 11. In onespecific embodiment, the upper staple 12 can have a width of about 2.0cm between its prongs, while the lower staple 11 can have a width ofabout 1.5 cm between its prongs 15. Of course, it is understood that thedimensions of the upper staple 12 and lower staple 11 are principallydetermined by the anatomy of the particular vertebra into which thestaples are engaged. In the specific example above, the staples aresized for engagement within a lumbar vertebra. It is further understoodthat while in the preferred embodiment the upper staple is wider thanthe lower staple, both staples can have essentially the same widthbetween their prongs.

[0069] The next element of the correction device 10 is the connectionmember 13. The connection member 13 includes an elongated machinethreaded shank 25 that bears external threads for mating with theinternal threads of the boss 17 of the lower staple 11. In one specificembodiment, the machine threaded shank 25 has a diameter of 0.30 cm with5-40 UNC 2A machine threads. The internal threads of the boss 17 aresimilarly configured for mating with the threaded shank 25. The lengthof the threaded shank 25 is determined by the vertebral anatomy.Preferably, the threaded shank 25 has a length sufficient to spansubstantially across the vertebral body. For firm engagement of theconnection member 13 between the upper and lower staples, it is alsopreferable that the threaded shank 25 have a length sufficient to extendsubstantially completely into the threaded boss 17. Likewise, it is alsopreferable that the threaded boss have a length that is sufficient for asolid threaded engagement between it and the threaded shank. In oneembodiment, the threaded boss 17 has a length that is greater than halfthe length of the threaded shank 25. In a specific embodiment, thethreaded shank 25 can have a length of about 45 mm, while the threadedboss 17 of the lower staple 11 has a length of about 25 mm.

[0070] In a further aspect of the connection member 13, an enlarged head26 is provided. A shoulder 27 is situated between the head 26 and themachine threaded shank 25. While the shank 25 is sized to fit through anopening 22 in the upper plate 21 of the upper staple 12, the shoulder 27has a diameter that is larger than the diameter of the opening 22. Inthis manner, the connection member 13 can apply a compressive forcebetween the upper and lower staples as the threaded shank 25 is threadedinto the boss 17. The shoulder 27 applies a force to the upper staple 12to push it toward the lower staple 11.

[0071] In a further aspect of the invention, the head 26 of theconnection member 13 is configured for engagement to an elongated memberextending along the spine adjacent the instrumented vertebrae. Inaccordance with the invention, the head 26 can assume a variety ofconfigurations provided that it can be firmly engaged to the elongatedmember. In the embodiment shown in FIGS. 1 and 2, the elongated memberis a spinal rod, such as a spinal rod provided with the TSRH® SpinalSystem. In the specific embodiment illustrated in FIG. 1, the head 26 isgenerally U-shaped defining a slot 29 between posts 33 forming theU-shape. The head 26 can also define tool recesses 30 on opposite sidesof the posts 33 so that the head can be gripped by a tool useful inthreading the shank 25 into the threaded boss 17.

[0072] The head 26 further defines an engagement face 31 that isoriented toward the elongated member, or spinal rod. In a specificembodiment, the engagement face 31 includes a plurality of radialsplines 32 emanating from the slot 29. In this illustrated embodiment,the head 26 of the connection member 13 is substantially identical tothe head of the Variable Angle Bone Screw sold by Danek Medical, Inc.This bone screw is also depicted in U.S. Pat. No. 5,261,909, owned bythe Assignee of the present invention. Specific reference is made toFIG. 2 of the '909 patent and its accompanying description at column 4,lines 10-23, which figure and text are incorporated herein by reference.The '909 patent further describes one manner in which the head of thevariable angle bone screw is engaged to a spinal rod. Specifically,reference is made to FIGS. 3-5 and the text at column 4, line 35 throughcolumn 5, line 47, which description is incorporated herein. Tosummarize, the head 26 of the connection member 13, just like the headof the variable angle bone screw, is engaged to a spinal rod by way ofan eyebolt and washer configuration. The washer includes splines thatcan mate with the splines 32 on the head 26. The washer also engages thespinal rod and permits connection of the head 26 to the spinal rod atvariable angular orientations. Again, the details of this type ofvariable angle connection are now well known as shown in the '909patent.

[0073] While the correction device 10 is used for a closing osteotomy,the correction device 40, depicted in FIG. 2, is provided for use in anopening osteotomy. Like the correction device 10, the device 40 includesa lower staple 41 and an upper staple 42. The lower staple 41 includesprongs 45 configured for penetration into the cortical bone of avertebra. A base plate 46 connects the prongs 45. Likewise, the upperstaple 42 includes a pair of prongs 50 connected by an upper plate 51.Like the upper staple 12, the upper staple 42 also defines an opening 52in the upper plate 51. The correction device 40 also utilizes theconnection member 13 which is, in the specific embodiment, identical tothe connection member 13 shown in FIG. 1. In that regard, the connectionmember 13 includes a shoulder 27 that prevents passage of the enlargedhead 26 through the opening 52 in the upper plate 51 of the upper staple42. The connection member 13 also includes an elongated machine threadedshank 25.

[0074] The connection device 40 further includes a wedge member 43 thatis configured to be disposed within the osteotomy site to maintain thepositioning of the portions of the vertebral body after the osteotomy isopened. Details of the lower staple 41 and the wedge member 43 that isengaged thereto, are shown in FIGS. 3-6. In one specific embodiment, thelower staple 41 includes a flat edge 47 and a curved edge 48. The wedgemember 43 includes a wedge body 55 that is preferably fixed to the lowerstaple 41, such as by welding. The wedge body 55 defines a threaded bore56 therethrough, that operates substantially similar to the threadedboss 17 of the lower staple 11 of the connection device 10 shown inFIG. 1. In particular, the threaded bore 56 can have a similar threadconfiguration to the threaded shank 25 of the connection member 13. Abore relief 57 is provided at the tapered end 61 of the wedge body 55.This bore relief 57 is preferably formed by angled faces convergingtoward the threaded bore 56. The relief 57 facilitates entry of thethreaded shank 25 of the connection member 13 into the threaded bore 56.

[0075] The wedge body 55 further includes a flat end face 58 that isaligned with the flat edge 47 of the lower staple 41. On the oppositeside of the wedge body 55 from the flat end face 58 is a curved face 60,which also corresponds to the curved edge 48 of the lower staple 41,both features being best shown in FIG. 5. The curved face 60 preferablyconforms substantially to the anterior perimeter of the vertebral body.The flat end face 58 is provided for clearance from the spinal foramenin the vertebra. It is understood, that in some specific embodiments,the wedge member 43 can be symmetrically shaped—that is, the wedge body55 can include a curved end face, such as end face 60, on both sides ofthe body.

[0076] In accordance with certain aspects of the invention, it isimportant that the wedge body 55 provide as large an area as possiblefor contacting the portions of the vertebral body at the osteotomy site.This contact occurs at the angled side faces 59, which are best shown inFIGS. 3 and 6. The angled side faces 59 define an angle between eachother that specifically corresponds to the amount of opening that isdesired at the osteotomy site. In a specific embodiment, the anglebetween the angled side faces 59 is 15 degrees. In one specificembodiment, the wedge body 55 has a height of about 1.25 cm from thebore relief 57 to the lower staple 41.

[0077] In a specific embodiment, the lower staple 41 can have a reliefbore 49 aligned with the threaded bore 56 of the wedge body 55. In thismanner, the connection member 13 can have a length sufficient topartially extend into the relief bore 49 of the lower staple 41. Furtherin this specific embodiment, the edge of the angled faces, and morespecifically the curved end face 60, is formed at a radius of 0.95 cm.Again, the dimensions of these features of the wedge member 43 can bemodified depending upon the anatomy of the vertebra within which thewedge member is engaged. Moreover, if greater or lesser wedge angles aredesired, the angle between the faces 59 can also be modified.

[0078] One specific manner of placement of the correction devices 10 and40 is shown in FIGS. 7A, 7B and 8. Looking first at FIG. 8, thecorrection device 10 is shown positioned in the anterior portion of thevertebral body. In particular, the connection member 13 spansessentially laterally across the vertebral body, with the lower staple11 and upper staple 12 penetrating the cortical bone of the vertebralbody. Preferably, the staples have a width sufficiently narrow to keepthem out of the adjacent discs D and fully contained within thevertebral body V. In the specific embodiment of the connection member13, the head 26 is oriented with its posts 33 aligned substantiallywithin the coronal plane. In this manner, connection of the head 26 ofthe member 13 to a spinal rod by way of an eyebolt occurs with thespinal rod extending along the length of the spine.

[0079] Looking at FIGS. 7A and 7B, the correction device 40 is depictedengaged within a vertebral body V. Again, the correction device 40extends transversely across the anterior portion of the vertebral bodywith the lower staple 41 and upper staple 42 penetrating the corticalbone. FIG. 7B illustrates the orientation of the wedge member 43 withinthe osteotomy site. It can be seen from this Figure that the curved face60 approximates the anterior edge of the vertebral body V. The flat endface 58 then provides clearance for the vertebral foramen F so that thewedge member does not impinge upon the spinal cord within the foramen.

[0080] The connection devices 10 and 40 are preferably formed of abiocompatible sterilizable medical grade material. In some specificembodiments, the components of the correction devices 10 and 40 can beformed of stainless steel, while in other applications titanium can bethe material of choice. In some embodiments, the wedge member 43 can bea solid member. In other embodiments, the wedge member 43 can be formedof a porous material, such as certain porous ceramics or a poroustantalum, such as HEDROCEL® produced by Implex Corporation.Alternatively, the wedge member 43 can include hollow portions withopenings in the angled side faces 59 in contact with the vertebral body.

[0081] One object of these specific embodiments of the wedge member 43is to permit tissue growth across and through the wedge member 43. Onegoal of the procedure of the present invention is to achieve bone unionof the portions of the vertebral body at the osteotomy sites. In thecase where the osteotomy is closed, bony material is in direct contactso that bone union can occur fairly easily and rapidly. On the otherhand, introduction of the wedge member 43 into an open osteotomy sitecan delay this bone union. Providing a wedge member 43 that allows fortissue growth through and/or into the wedge member can enhance thelikelihood and rate of bone union of an open osteotomy site. In aspecific preferred embodiment, the wedge member 43 is preferably formedof the porous tantalum HEDROCEL® material which not only permits bonegrowth through the wedge member 43, but also allows the member to befully integrated into the resulting bone union.

[0082] In an alternative embodiment, the connection member 13 for thecorrection devices 10 and 40 can be replaced by a connection member 65as depicted in FIGS. 9 and 10. The connection member 65 includes athreaded shank 66 that can be identical to the threaded shank 25 of theconnection member 13. The primary difference between connection member65 and the prior member is that the head 67 of member 65 is configuredto directly receive a spinal rod therein. Specifically, the head 67includes a pair of opposite arms 68 which form a U-shaped rod channel 69therebetween. The rod channel 69 has a width and diameter that is justslightly larger than the diameter of a spinal rod so that the rod can beseated within the channel. The arms 68 further define an internallythreaded bore 70 that intersects the rod channel 69. A threaded plug(not shown) can be used to clamp the rod within the rod channel bythreading into the threaded bore 70. The head 67 of the connectionmember 65 of the present embodiment can be similar to the head ofcertain bone screws provided with the CD®, CCD® and CD Horizon® SpinalSystems sold by Sofamor, S.N.C., a subsidiary of Sofamor Danek Group.Some details of the construct can also be found in U.S. Pat. No.5,147,360, assigned to Sofamor, S.N.C. Particularly, FIG. 5 of the '360patent, together with the specification at column 4, lines 44-55, whichdisclosure is incorporated herein by reference, show one embodiment of ahead of a bone screw for use with the present invention.

[0083] In the preferred embodiment, connection member 65 is preferredsince it permits top-loading introduction of the rod into the head ofthe member when the correction devices 10, 40 are implanted within thepatient. It is understood that different head configurations for theconnection members can be provided depending upon the type of elongatedmember extending along the length of the spine and the type ofconnection desired. For example, if the elongated member extending alongthe length of the spine is a plate, the head, such as head 26 ofconnection member 13, can be in the form of a machine threaded post.This machine threaded post could then be engaged through a slot in theelongated plate by way of a nut. Such a connection is accomplished inthe DYNALOK® bone bolt and plate sold by Danek Medical, Inc. Details ofsuch a connection can also be found in U.S. Pat. No. 5,545,163, assignedto Danek Medical, Inc., and particularly in FIGS. 6 and 10 and theiraccompanying descriptive text, which is incorporated herein byreference. Alternatively, the head of the connection member can beclosed, meaning that the elongated member spanning the length of thespine must be threaded through an opening defined in the head of theconnection member. Regardless of the manner in which the connectionmember is engaged to a particular elongated member spanning the spine,in order to achieve one object of the invention, the elongated membershould be capable of removal once bone union occurs at the osteotomysites.

[0084] An example of using the correction devices 10 and 40 of thepresent invention, along with the inventive surgical techniques, can beunderstood with reference to FIGS. 11- 14C. Referring first to FIG. 11,a portion of a patient's spine from T₃ to the sacrum is shown in whichthe spine has a scoliotic curve. As can be seen in the Figure, the apexof the curve is offset a distance D from its correct alignment in thecoronal plane. In other words, the spine is deformed laterally so thatthe axes of the vertebral bodies are displaced from the sagittal planepassing through the spine of the patient. It should be understood thatthe spinal deformity depicted in FIG. 11 is but one of many types ofspinal deformities that can be addressed by the devices and techniquesof the present invention. Most commonly the devices and techniques areexpected to be used for either primary thoracic or thoracolumbar curves.They can be used for correction of the thoracic curve as an isolatedcurve, or the lumbar curve as an isolated curve.

[0085] In correcting the curved deformity shown in FIG. 11, wedgeosteotomies R₆-R₁₁ can be cut from the thoracic vertebra T₆-T₁₁ at theconvex side of the curvature. Preferably, a 15 degree osteotomy wedge ofbone from the vertebral body is removed, although other wedge dimensionscan be accommodated depending upon the amount of curvature and lateraloffset of the particular vertebra. In the lumbar spine, openingosteotomies X₁-X₄ are shown cut into the vertebra L₁-L₄. They could becut into T₁₁ to L₄. In the lumbar spine for this particular curvature,no bone material is removed. Instead, the vertebral body is essentiallyfractured to permit an opening osteotomy at that vertebral level. Again,the cut into the lumbar vertebrae occurs on the same side of the spineas the wedge osteotomies in the thoracic vertebrae. The variousosteotomies in the thoracic and lumbar vertebrae can be performed usingconventional tools and instruments, such as a chisel and an osteotomyspreader.

[0086] Once the osteotomy sites have been prepared in each of theaffected vertebrae, the spine can be manipulated to close the closingosteotomies R₆-R₁₁ and open the lumbar osteotomies X₁-X₄. The spinewould then appear as shown in FIG. 12 in which the thoracic osteotomiesare closed at sites C₆-C₁₁ and the lumbar osteotomy sites are left openat sites W₁-W₄. In the configuration shown in FIG. 12, the lateraloffset of scoliotic curvature is reduced to an offset D′ that issignificantly less than the original curvature deformity. Ideally, theoffset D′ would be negligible so that the spine would appear properlyaligned in the coronal plane.

[0087] The determination of the location and nature of the opening andclosing osteotomies can be determined after a review of A-P and lateralradiographs of the spinal deformity. In some senses, the identificationof the osteotomies is a matter of geometry. For example, in the thoracicspine, each closing osteotomy will eliminate a certain amount of theabnormal curvature as the osteotomy is closed as shown in FIG. 12.Similarly, each opening osteotomy in the lumbar spine will cause aneffective translation of the particular lumbar vertebra toward thespinal midline. The amount of effective shifting of the axis of a lumbarvertebra toward the spinal midline can be based upon the size of theopening wedge osteotomy performed at that vertebra. It is, however,preferable that the opening or closing wedge osteotomies not exceed a 15degree segment removed from or added to the vertebral body, in order topreserve the vertebral architecture as much as possible and to reducethe possibility of narrowing of the disc space.

[0088] Once the thoracic osteotomies are closed and the lumbarosteotomies are opened, the correction devices 10 and 40 can be engagedto the respective vertebrae. For example, the correction device 10 isengaged to the thoracic vertebrae, with the lower staples 11 positionedon one side of the vertebral body, and upper staples 12 positioned onthe contra-lateral side of the vertebral body. The connection member,which can be member 65 in FIG. 9, is then engaged between the upper andlower staples. In preparation for engagement of the connection member65, a bore can be formed laterally through the vertebral bodyessentially through the centerline of the osteotomy. In certaintechniques, the centerline of the osteotomy will extend laterallythrough the vertebral body and generally intersecting the center of thebody. The bore can be prepared using a conventional drill or even usinga curette.

[0089] A similar procedure is performed to introduce the correctiondevice 40 to the lumbar vertebrae. In this instance, the wedge members43 are disposed within the open osteotomy sites W₁-W₄. The lower andupper staples 41, 42, respectively, are then engaged to the vertebralbodies. The staples of both correction devices 10 and 40 are used topress the halves of the vertebral body together to close the osteotomysite as in the thoracic vertebrae, or to press the vertebral halvesagainst the wedge member 43. Prior to closing each of the osteotomies,bone fusion material or bone cement can be introduced into the osteotomysite to facilitate complete closure and ultimate bone union.

[0090] Once the correction devices 10 and 40 are engaged to theirparticular vertebrae, the elongated member, such as spinal rod 72, canbe engaged to each of the connection members 65 in the manner describedabove. Depending upon the configuration of the spine after performanceof the osteotomies, the spinal rod 72 may be pre-bent to a particularcurvature. In the configuration shown in FIG. 13, a certain amount oflateral curvature remains so that the rod would be pre-bent to emulatethat lateral curvature. Further straightening of the spine can beaccomplished if the rod 72 does not completely emulate the intermediatecorrected curvature. In that instance, some widening and narrowing ofthe intervertebral disc space may occur, but it may be expected that thedisc space height would be restored once the spinal rod 72 is removed.

[0091] In addition to any residual lateral curvature following theimplantation of the correction devices, the spinal rod 72 is preferablybent to correspond to the normal kyphotic and lordotic curvatures of thethoracic and lumbar spine segments. In this manner, the flat backsyndrome can be avoided. Care must be taken that the sagittal planecurvature of the spinal rod 72 not exceed the physiologic capability ofthe spinal segments. In other words, the deformed spine of a patient mayalso have a curvature deformity in the sagittal as well as the coronalplanes. Under some circumstances, the rod rolling technique frequentlyutilized with the CD® Spinal System can also be implemented where anintermediate corrected residual curvature remains. In that instance,pre-bending the rod 72 to conform to that residual curvature, such asshown in FIG. 13, can also approximate the normal kyphotic and lordoticcurvatures for a healthy spine. Thus, it can be contemplated that therod 72 shown in FIG. 13 can be rolled about its axis so that the spinebecomes perfectly aligned in the coronal plane with the restoration ofthe normal curvature in the sagittal plane. Also, separate rods anddifferent rod locations may be used for addressing thoracic spineproblems separate from lumbar spine problems.

[0092] In accordance with a preferred technique of the presentinvention, the correction devices 10 and 40 and the spinal rod 72 areimplanted from an anterior approach. In contrast to prior techniques forthe correction of scoliosis, only a single rod is required to maintainthe stability of the correction. Since the physiology of the discs andvertebrae are not being changed, the elastic strength of theintervertebral discs will help retain the spinal column in its correctedconfiguration. Where each of the vertebral bodies is held together byway of staples on opposite sides of the body, there is substantially norisk that the osteotomy sites will separate or fail. Thus, it can beseen that the present invention takes advantage of the natural strengthof the spine in order to retain the stability of the temporary fixationat least until bone union occurs. Depending upon the overall health ofthe patient and of the vertebral bodies, this bone union can occur in amanner of a few months.

[0093] Once bone union has occurred and the vertebral bodies areessentially healed, the spinal rod 72 is no longer essential to maintainthe stability of the spine. In this case, the rod 72 can be removed bydisconnecting it from each of the connection members 13 or 65, leavingonly the head of the connection member projecting beyond the vertebralbody. At this point, the intervertebral discs resume their normalfunction and the patient's spinal column is as close to a normalconfiguration as possible. While the preferred embodiment of theinvention envisions completely removing the spinal rod and associatedconnectors, such as eyebolts and machine threaded nuts, a biodegradableor resorbable rod can also be contemplated. In this instance, the rodwould gradually resorb. Similarly, the correction devices 10 and 40 alsobecome superfluous once bone union is achieved at the osteotomy site.Thus, the components of the correction devices can also be resorbable.One example previously discussed is the formation of the wedge member 43out of a porous tantalum or HEDROCEL® material. A similar material maybe usable to form the staples and the connection members, provided thatthe material forming these components can still meet their strengthrequirements.

[0094] In certain applications of the devices of the present invention,the spinal rod or elongated member may not be necessary to stabilize theinstrumentation. For instance, if only a few vertebrae are instrumentedwith a correction device, the elongated spinal member or rod may not berequired. Since the present invention contemplates correction of spinaldeformities without fusion, additional fixation devices are not asessential as in other procedures in which fusion occurs. In those otherprocedures, the spinal segments must be essentially immobilized in orderfor the bony bridge to be formed across the intervertebral disc space.These same requirements are absent in the present inventive techniqueusing the novel devices described above. In the instance in which aspinal rod is eliminated, it is of greater importance that the upper andlower staples hold their position within the vertebral body to therebyhold the osteotomy sites in their preferred orientation. Thus, theconnection members 13, 65 as previously described, provide a compressiveforce between the upper and lower staples to hold them within thevertebral body. It is understood, that this compressive force is not sogreat as to cause subsidence of the staples within the vertebral body.In cases in which the spinal rod 72 is not utilized, the connectionmember 13, 65 does not require the presence of a head 26, 67 which wouldordinarily be engaged to the spinal rod. Instead, the connection membercan be modified to simply include an enlarged shoulder 27 with a drivingtool recess formed in the shoulder to receive a driving tool forthreading the threaded shank 25, 66 of the connection member into thethreaded boss 17 or the threaded bore 56. In the cases in which thespinal rod is eliminated, the vertebrae will be held in their correctedposition by the elasticity of the intervertebral discs. Since thegeometry of the vertebral bodies has been altered, the spine shouldautomatically assume its corrected position, even without the assistanceof an additional member spanning the spine.

[0095] The present invention also contemplates a surgical technique inwhich curvature deformities in multiple planes can be corrected. Forinstance, in many cases, the patient's spine suffers not only fromscoliosis, but also from some degree of kyphosis or lordosis. In thisinstance, correction of an abnormal curvature must occur in two planes.The present invention readily permits such a correction.

[0096] As shown in FIG. 14A, the vertebral body V has an axis Z from thecenter of the vertebral body directed posteriorly and an axis Y directedlaterally within the coronal plane. In cases where the particularvertebral body is misaligned in two planes, the centerline of theosteotomy 75 can be oriented at an angle a relative to the axis Y. Inthe procedures previously described, the centerline 75 of the osteotomycorresponds or is aligned with the axis Y. As can be seen in FIGS. 14Band 14C, removal of bone material for a closing osteotomy R, or additionof a wedge member for an opening osteotomy W is depicted. The angularorientation of the osteotomy at the angle a achieves correction andre-alignment of the vertebra in two planes.

[0097] Referring now to FIGS. 15-18, the correction device 80 is showntherein, is similar in many respects to that of FIG. 2. For example, itincludes a bone-piercing device 81 in the form of a staple very similarto the staple 42 in FIG. 2. It also includes a bone-piercing device 82at the opposite end and also in the form of a staple, althoughconsiderably modified in shape to better fit the surface of theintervertebral body as best shown in FIG. 19A, thereby matching theprofile of the concave portion of the vertebral body. It also includes awedge 83, a screw 84, and a head 86. There are some differences whichwill be described now.

[0098] Viewed as shown in FIG. 18, the staple 82 described briefly abovehas a shape suggesting an inverted gull-wing or a wide “W”. The wedge 83is fixed to the staple 82 by welding, press fit or any other suitablemeans at 87. The wedge has a plurality of apertures 88 through it whichserve to reduce mass and encourage bone growth through the wedge. Thescrew 84 is fixed to the wedge at 89 and/or staple 82 by welding, pressfitting or otherwise.

[0099] The head 86 has internal threads which are threaded onto theexternal threads 91 extending from the outer end 92 of the screw. Thehead-end bone-piercing anchoring device 81 has a central aperture 93through it, with a chamfer 94 at the top. The head has the outwardlyopening U-shaped channel 96 opening at the outer end 97 thereof toreceive a spinal rod such as 72 (FIGS. 13, 19A, 19B). There are also theusual tool receiver opening such as 98 and 99 that are usually providedfor this type of head which has been in use by the assignee of thesubject application and marketed under the assignee's CD Horizon® brand.The head may be of other shapes for other styles of devices forintervertebral attachment.

[0100] Further referring to head 86, the oppositely facing flat outersurfaces 101, and curved outer surfaces 102 blend into a base 103 havingthe concave surface blending from those faces into the base toward theinner end 104 of the base. This concave surface can successfully seat atthe outer face 106 (FIG. 18) of the bone-piercing anchor device 81without the surface 106 being in a plane perpendicular to the screw axis85. In this way, good anchorage in the vertebral body can be achievedeven if one or the other of the two prongs of the piercing device 81does not fully penetrate the vertebral body. Also it enables the outerportions 107A and 107B of surface 107 to contact the vertebral body,even if the axis of aperture 93 is not colinear with axis 85 of thescrew. Here it should be mentioned that the head-end anchor 81 can beshaped such that, as viewed in the direction represented in FIG. 18, itwould suggest a wide “M” or a gull wing appearance like that of anchor82, but not inverted. This could be used to conform the shape of thehead-end anchor more closely to the profile of the vertebral body, ifdesired.

[0101] In the use of the FIGS. 15-18 embodiment of the invention, theprocedure described above with reference to the lumbar spine in FIG. 11,can be followed. After performing the opening osteotomy and providing ahole through the vertebral body, the threaded end of the screw isinserted from one side of the vertebral body in the direction of arrow111 in FIG. 19A. Then, with the bone piercing anchor 81 installedloosely on the base 103 of the head 86, the head is screwed onto thethreads 91 of the screw 84, with the first and second anchors 82 and 81oriented as shown in FIG. 19A. These devices are maintained in thisattitude as the head is advanced on the screw threads until both thesharp edges of the prongs of the anchors are thoroughly seated in thevertebral body. Then the screw threads extending outward beyond thecountersink 112 (FIG. 18) in the head, can be clipped or broken off withtooling already known in the art for performing that step with the CDHorizons instrumentation or other instrumentation known in the art. Bonefusion material or bone cement can be introduced into the holes 88 inwedge 83 prior to insertion of the screw, if desired, to enhance thefunction of whatever bone fusion material or bone cement may havealready been introduced into the osteotomy site prior to installation ofthe screw.

[0102] After the desired correction devices have been installed in thevertebral bodies in the manner described above, the rod 72 as previouslydescribed, is installed in the slots 96 and clamped in place by the setscrew 116 threaded into the threads 117 of the head 86 in FIG. 19B. Asshown in FIG. 19A, the inwardly facing surfaces 82A and 82B generallyconform to the curvature of the concave side of the vertebral body. Thebone-piercing edges 82C of the device 82, and which, when combined withthe surfaces 82A and 82B present in FIG. 18 the appearance of “birdbeaks”, are thereupon securely anchored in the vertebral body. Also, itshould be noted in FIG. 18, that the sharp end 81 A and 81B of thebone-piercing prongs of the member 81 are spaced at a slightly greaterdistance than at the bends 107A and 107B, providing a slight inwardtaper to assist this member 81 in anchoring in the bone and holding thebone snug against the angled side faces of the wedge.

[0103] Referring now to the embodiment in FIGS. 20 through 25, all ofthe features of this embodiment are the same as those in the embodimentof FIGS. 15-19B except for elimination of one of the prongs of each ofthe head-end bone-piercing device 121 and the wedge-end bone-piercingdevice 122. The installation is much the same as described above for theembodiment of FIGS. 15-19B and shown in FIGS. 19A and 19B. As shown inFIG. 26, the preference is to have the bone-piercing device at each ofthe head end and wedge end of the assembly above the screw axis and thescrew axis slightly below the coronal mid-plane of the vertebral body.As shown in FIG. 22, the upper bone-piercing member has a sharpenedstraight edge 121 A, like 81A of the FIG. 15 embodiment and the centralopening 123 with the upper edge chamfer 124 in the ring portion 125 ofthis device. The wedge end of bone-piercing device 122 has an aperture126 through it which receives the wedge end 84W of screw 84 which, asmentioned above, is identical to that in the FIG. 15 embodiment. Also asindicated above, the screw and wedge and bone-piercing device can bewelded together or press fit or otherwise fixed together in any desiredway such as welding at the bolt 26 in the wedge and bone anchor 122 andthe hole 83H in the wedge.

[0104] In the FIG. 26 installation, like those in FIGS. 7A, 7B, 19A and19B, the curved anterior edge 83A of the wedge 83 conforms to theanterior perimeter of the vertebral body at the osteotomy site. Theshape of the posterior edge 83P, and the proximity of the edge 83P tothe screw axis, assure avoidance of the spinal foramen.

[0105] Referring now to FIGS. 27 through 29, this embodiment of theinstrumentation is proposed for those cases in which the spinaldeformity is sufficiently mild that reasonable correction can beobtained by opening wedge osteotomies, but without intervertebralconnection. In this connection device 130, there is the bone piercingdevice 131 virtually identical to device 121 in FIG. 20. It is receivedon the screw 134 which has the lower bone piercing device 132 at thelower end, wedge 133 immediately above it, and a head 136 at the top.The lower bone piercing device 132 serves as an anchor in basically thesame manner as described above with reference to FIG. 26 and is weldedto the lower end 137 of the screw as at 138, for example. The wedge 133may be welded to the screw at 139 or to the anchor 132.

[0106] The upper bone piercing device 131 has a central aperture 141with a chamfer 142 at the upper edge of the opening on which is a convexsurface 143 (typically spherical) of the head 136 is bearing when thehead is screwed onto threads 146 with which the internal threads 144 ofthe head are mated. As described with reference to previous embodiments,the spaces between thread sets are narrowed so that, after installationof the connection device, and depending upon the distance between thetwo anchors, a portion of the upper end of the screw may extend beyondthe top of the head 36 and can be broken off to provide a flush surfaceas shown in FIGS. 27 through 29.

[0107] As shown in FIG. 28, the wedge is shaped so that the anterioredge 133 will somewhat conform to the shape of the intervertebral bodyas shown for the wedge 83 in FIG. 19B for that embodiment of theinvention. Also, the posterior edge 133P of wedge 133 is close to thelongitudinal axis of the screw to adequately space it from the spinalforamen. Apertures 147 in the wedge are provided for the same reason asdiscussed above.

[0108] Referring now to FIGS. 30 through 32, all features of thisembodiment are the same as in the previously described embodiment exceptfor the head. In this embodiment, while the head 151 has an externalhexagonal surface as in the previously described embodiment, it isslightly different in the respect that the head is larger in a radialdimension with respect to the axis of the screw 134. It also has a wall151W radially spaced from the screw axis and which has an aperture 152through it. it. This embodiment of the present invention is intended foruse in those applications where a metal cable or plastic tether such asof braided polyethylene may be used to make connections between theinstrumentation of this type in one vertebral body, and that in anothervertebral body. Such connections may be made between adjacent vertebralbodies, or vertebral bodies that are spaced from each other with othervertebral bodies in the space. As in the previously describedembodiment, depending upon the distance of the anchors 131 and 132 afterthe instrumentation is installed in the vertebral body, if any portionof the upper end of the screw 134 extends above the shelf 153 of thehead, that portion of the screw can be broken off.

[0109] It should be understood from the foregoing description of theembodiments of FIGS. 27 through 31, that the procedure for use is muchthe same as that described above with reference to FIGS. 15 through 26.

[0110] The present invention provides a surgical technique that permitscorrection of spinal deformities without the need for fusion of theintervertebral discs. The osteotomies conducted according to thetechnique can be done rapidly using conventional instruments while stillprotecting the spinal cord and controlling bleeding. The use of stapleson opposite sides of the vertebral body maintain the osteotomy sites intheir required configuration for bone union to occur. Ancillary supportfor the instrumented vertebrae can be provided by way of a removableelongated member spanning the spine, such as a spinal rod. Unlike priortechniques in which fusion of the disc space is performed, the spinalrod need not bear as much of the spinal loads as in the otherprocedures. Thus, the rod can have a smaller diameter than traditionalspinal instrumentation rods. An ultimate goal of the present inventionis removal of the spinal rod once bone union has occurred at theosteotomy site. The present invention contemplates application to a widevariety of spinal deformities, although correction of scoliosis may be aprincipal application.

[0111] While the invention has been illustrated and described in detailin the drawings and foregoing description, the same is to be consideredas illustrative and not restrictive in character, it being understoodthat only the preferred embodiments have been shown and described andthat all changes and modifications that come within the spirit of theinvention are desired to be protected.

What is claimed:
 1. An apparatus for use in the correction of spinaldeformities, comprising: a first anchor having at least one prongconfigured to penetrate one side of a vertebral body of a vertebra to becorrected; and a second anchor having at least one prong configured topenetrate an opposite side of said vertebral body of the vertebra to becorrected; means for extending through said vertebral body for pullingsaid first anchor toward said second anchor when said anchors penetratesaid vertebral body on substantially opposite sides of said vertebralbody.
 2. The apparatus of claim 1 and wherein: each of said anchors hasanother prong, and is a staple.
 3. The apparatus of claim 1 , whereinsaid means for pulling said first anchor toward said second anchorincludes: an elongate member having a longitudinal axis and sized toextend through the vertebral body and between the opposite sides of thevertebral body, said member having one end and an opposite end andhaving a wedge extending from said first anchor and a threaded shankextending from the opposite end; and a head threaded onto said shank,said second anchor defining an opening therethrough smaller than saidhead.
 4. The apparatus of claim 3 , wherein said second anchor isL-shaped, having a proximal portion with said opening centered on saidaxis, with said prong having a first portion extending radially fromsaid proximal portion and said prong having a second portion spaced fromsaid axis and extending generally parallel to said axis, toward saidfirst anchor and having a sharp distal end to penetrate said vertebralbody.
 5. The apparatus of claim 3 wherein: said head has a convex lowersurface engaging said second anchor.
 6. The apparatus of claim 5wherein: said head has a hexagonal tool-receiver outer surface.
 7. Theapparatus of claim 5 wherein: said second anchor has a sloped surfaceengaged by said convex surface of said head.
 8. The apparatus of claim 3wherein: said head has a receiver aperture therethrough for a flexibleconnector.
 9. The apparatus of claim 8 wherein: the receiver aperturehas an axis generally transverse to said longitudinal axis.
 10. Theapparatus of claim 9 wherein: said head has a tool receiver surfacethereon engageable by an external tool for installing said head on saidshank; and said head has a wall extending generally parallel to the saidlongitudinal axis of said elongate member; and said wall has saidaperture therethrough for reception of a cable therethrough.
 11. Theapparatus of claim 10 wherein: said tool receiver surface is hexagonal.12. The apparatus of claim 3 wherein: said second anchor has a secondprong configured to penetrate said opposite side of said vertebral body;said second anchor having a proximal portion with said opening centeredon said axis, and with each of said prongs having first portionsextending radially from said proximal portion and said prongs havingdistal portions spaced from said axis and extending generally parallelto said axis toward said first anchor and having a sharp distal end topenetrate said vertebral body.
 13. The apparatus of claim 3 , whereinsaid head defines a circumferential surface for engaging said secondanchor adjacent said opening.
 14. The apparatus of claim 3 , whereinsaid head defines a channel therethrough for receiving an elongate rodtherein.
 15. The apparatus of claim 3 wherein: said threaded shankincludes a plurality of spaced sets of external threads for mating withsaid head, said sets of threads being spaced along the shank from theopposite end and having reduced cross sectional areas between the setsand adopted to breaking away a length of the shank extending from theopposite end toward the one end at a location selected to clear thechannel for admission of said elongate rod.
 16. The apparatus of claim15 and further comprising: a set screw, operable to secure said rod insaid channel; the head having threads spaced from said shank andthreadedly receiving said set screw in said head.
 17. The apparatus ofclaim 16 and wherein: said set screw is a break-off set screw.
 18. Theapparatus of claim 1 , wherein: said means for pulling said first anchortoward said second anchor includes an elongate member having alongitudinal axis and sized to extend through the vertebral body andbetween the opposite sides of the vertebral body; and said first anchorhas a proximal portion connected to one end of said elongate member, andsaid one prong has a first portion projecting radially outward from saidproximal portion and away from said second anchor to a location radiallyspaced from said elongate member, and said one prong has a secondportion turning from said first portion toward said second anchor andterminating at a sharp distal end.
 19. The apparatus of claim 18wherein: said second portion of said one prong has surfaces beginning atsaid location of said turning from said first portion and converging tosaid sharp distal end.
 20. The apparatus of claim 1 and wherein saidmeans for pulling said first anchor toward said second anchor includesan elongate member having a longitudinal axis and sized to extendthrough the vertebral body and between the opposite sides of thevertebral body; said first anchor has a proximal portion connected toone end of said elongate member, and said one prong has a first portionprojecting radially outward from said proximal portion and away fromsaid second anchor to a location radially spaced from said elongatemember and said one prong has a second portion turning toward saidsecond anchor and terminating at a sharp distal end; said first anchorhas a second prong which has a first portion projecting radially outwardfrom said proximal portion and away from said second anchor to alocation radially spaced from said elongate member, and said secondprong has a second portion turning toward said second anchor andterminating at a sharp distal end.
 21. The apparatus of claim 20 andwherein: said first and second portions of said first and second prongscombine with said proximal portion connected to said one end of saidelongate member whereby said first anchor has an inverted gull wingconfiguration.
 22. The apparatus of claim 1 , wherein said means forpulling said first anchor toward said second anchor includes: anelongate member having a longitudinal axis and sized to extend throughthe vertebral body and between the opposite sides of the vertebral body,said member having one end and an opposite end and having a wedge at theone end and a head at the opposite end; the wedge being configured tofill at least a portion of an osteotomy site in the vertebral body. 23.The apparatus of claim 22 wherein: the wedge has angled faces and firstand second oppositely-facing ends, one of the ends being shaped toconform to the shape of a portion of the perimeter of the vertebral bodyat the osteotomy site.
 24. The apparatus of claim 23 wherein: the otherof the ends of the wedge is located proximate the axis of the elongatemember to avoid the spinal foramen of the vertebral body.
 25. Theapparatus of claim 22 wherein: said wedge has a plurality of aperturestherein to enable vertebral tissue to grow through said apertures. 26.The apparatus of claim 25 and wherein: the elongate member is a threadedshank having threads thereon threadedly engaging at least one of thewedge or the head.
 27. The apparatus of claim 26 wherein: said firstanchor has a proximal portion connected to one end of said elongatemember, and said one prong has a first portion projecting radiallyoutward from said proximal portion and away from said second anchor to alocation radially spaced from said elongate member and said one pronghas a second portion turning toward said second anchor and terminatingat a sharp distal end; said first anchor has a second prong which has afirst portion projecting radially outward from, said proximal portionand away from said second anchor to a location radially spaced from saidelongate member, and said second prong has a second portion turningtoward said second anchor and terminating at a sharp distal end, wherebysaid first anchor has a shape that generally conforms to the concaveprofile of the vertebral body.
 28. The apparatus of claim 27 wherein:said second anchor has a second prong configured to penetrate saidopposite side of said vertebral body; said second anchor having aproximal portion with said opening centered on said axis, and with eachof said prongs of said second anchor having first portions extendingradially from said proximal portion and said prongs having distalportions spaced from said axis and extending generally parallel to saidaxis toward said first anchor and having a sharp distal end to penetratesaid vertebral body.
 29. The apparatus of claim 28 and wherein: saidfirst and second portions of said first and second prongs of said firstanchor combine with said proximal portion connected to said one end ofsaid elongate member whereby said first anchor has a wide ‘W’configuration.
 30. A method for correction of a spinal deformity of apatient, comprising the steps of: identifying a first group of vertebraeto be corrected; performing an osteotomy on each vertebra of the firstgroup; closing the osteotomy in each vertebra in the first group; andengaging a first staple to each vertebra in the first group to hold theosteotomy closed.
 31. The method for correction of a spinal deformity ofclaim 30 , in which the deformity is scoliosis and wherein: the firstgroup of vertebrae form a lateral curve in the coronal plane; and theosteotomy is performed on the first group on the convex side of thelateral curve.
 32. The method for correction of a spinal deformity ofclaim 30 , further comprising the steps of: engaging a connection memberto each vertebra in the first group; and connecting each connectionmember to an elongated member spanning the first group of vertebrae. 33.The method for correction of a spinal deformity of claim 32 , in whichthe steps of engaging a connection member and connecting each connectionmember to an elongated member occur on the anterior aspect of eachvertebra in the first group.
 34. The method for correction of a spinaldeformity of claim 32 , further comprising the steps of disconnectingeach connection member from the elongated member and removing theelongated member from the patient once bone union of the osteotomy sitesin the first group of vertebrae is achieved.
 35. The method forcorrection of a spinal deformity of claim 30 , further comprising thestep of: engaging a second staple to each vertebra in the first group onsubstantially an opposite side of the vertebral body from the firststaple.
 36. The method for correction of a spinal deformity of claim 35, further comprising the step of: engaging a connection member to thefirst and second staples and extending through the vertebral body. 37.The method for correction of a spinal deformity of claim 36 , furthercomprising the step of: connecting each connection member to anelongated member spanning the first group of vertebrae.
 38. The methodfor correction of a spinal deformity of claim 30 , further comprisingthe steps of: identifying a second group of vertebrae to be corrected;performing an opening osteotomy on each vertebrae of the second group;inserting a wedge member into the osteotomy site of each vertebra of thesecond group; and, engaging a staple to each vertebra of the secondgroup to hold the wedge member within the osteotomy site.
 39. The methodfor correction of a spinal deformity of claim 38 , in which thedeformity is scoliosis and wherein: the second group of vertebrae form alateral curve in the coronal plane; and the osteotomy is performed onthe second group on the concave side of the lateral curve.
 40. Themethod for correction of a spinal deformity of claim 38 , furthercomprising the steps of: engaging a connection member to each vertebrain the first and second groups; and connecting each connection member toan elongated member spanning the first and second groups of vertebrae.41. A method for correction of a spinal deformity of a patient,comprising the steps of: performing an osteotomy on a plurality ofvertebrae; inserting a wedge member into the osteotomy site in each ofthe plurality of vertebrae; and engaging a first staple to each vertebrain the first group to hold the wedge member within the osteotomy site.42. The method for correction of a spinal deformity of claim 41 , inwhich the deformity is scoliosis and wherein: the plurality of vertebraeform a lateral curve in the coronal plane; and the osteotomy isperformed on the plurality of vertebrae on the concave side of thelateral curve.
 43. The method for correction of a spinal deformity ofclaim 41 , further comprising the steps of: engaging a connection memberto each of the plurality of vertebrae; and connecting each connectionmember to an elongated member spanning the plurality of vertebrae. 44.The method for correction of a spinal deformity of claim 43 , in whichthe steps of engaging a connection member and connecting each connectionmember to an elongated member occur on the anterior aspect of thevertebra.
 45. The method for correction of a spinal deformity of claim43 , further comprising the steps of disconnecting each connectionmember from the elongated member and removing the elongated member fromthe patient once bone union of the osteotomy sites in the plurality ofvertebrae is achieved.
 46. The method for correction of a spinaldeformity of claim 41 , further comprising the step of: engaging asecond staple to each of the plurality of vertebrae substantially onopposite sides of the vertebral body from the first staple.
 47. Themethod for correction of a spinal deformity of claim 46 , furthercomprising the step of: engaging a connection member to the first andsecond staples and extending through the vertebral body.
 48. The methodfor correction of a spinal deformity of claim 47 , further comprisingthe step of: connecting each connection member to an elongated memberspanning the plurality of vertebral.
 49. The method for correction of aspinal deformity of claim 41 , wherein the step of inserting a wedgemember includes providing a wedge member formed of a porous material andintroducing an osteogenic material into the wedge member.
 50. The methodfor correction of a spinal deformity of claim 41 , wherein said step ofinserting a wedge member includes providing a wedge member havingopposite angled faces and a flat side face between the angled faces andorienting the wedge member within the osteotomy site with the angledfaces contacting the vertebral body and the flat side adjacent thespinal foramen. engaging a staple to each of the second group ofvertebrae to hold the wedge member within the osteotomy site.
 51. Amethod for correction of a spinal deformity of a patient, comprising thesteps of: performing an osteotomy on a plurality of vertebrae; applyinga staple to each of said plurality of vertebrae to maintain theosteotomy site in a predetermined orientation; engaging a couplingmember to a predetermined number of the plurality of vertebrae;providing an elongated rod bent to a predetermined curvature; andengaging each of the coupling member to the elongated rod.
 52. A methodfor correcting a spinal curve deformity of a patient, comprising thesteps of: bending an elongated rod to a predetermined curvature for thespine of the patient; for each of a plurality of vertebrae, identifyingthe misalignment of the vertebra in the sagittal and coronal planes; foreach of the vertebrae, performing an osteotomy at an orientation in thevertebral body to substantially approximate the sagittal and coronalplane misalignment of the respective vertebrae to the predeterminedcurvature; closing the osteotomy site of certain ones of the vertebraeto substantially approximate the predetermined curvature at therespective vertebra; engaging a wedge member within the osteotomy siteof others of the vertebrae to substantially approximate thepredetermined curvature at the respective vertebra; engaging a staple atthe osteotomy site of each of the plurality of vertebrae to maintain therespective vertebra in its approximate position; and engaging at leastthree of the plurality of vertebrae to the elongated rod.